Sudden power loss causes damage?

  • Thread starter Thread starter John Doe
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J

John Doe

Are modern hard disk drives susceptible to hardware damage or data
corruption from sudden power loss?

By "sudden power loss", I mean like if you pull the power supply plug
out off the wall socket, or if the hard disk drive power cable is
disconnected.

Partly curious. Thank you.
 
Modern journalling file system are sufficiently robust against power loss,
but any unwritten DATA may be lost, causing corruption in the user's files
structure.

Don't take chances and buy an UPS.
 
If the drive is writing, the current sector will be bad. Documented in many
drive manuals, and also the servo chipset docs.

The drive will always retract the heads to landing zone or offload ramp.
 
Are modern hard disk drives susceptible to hardware
damage or data corruption from sudden power loss?
Click to expand...

Nope, they should all handle that with no data loss or damage.
By "sudden power loss", I mean like if you pull the power supply plug
out off the wall socket, or if the hard disk drive power cable is
disconnected.
Click to expand...
Partly curious. Thank you.
Click to expand...

You know what that did to the cat dont you ?
 
Previously John Doe said:
Are modern hard disk drives susceptible to hardware damage or data
corruption from sudden power loss?
Click to expand...
By "sudden power loss", I mean like if you pull the power supply plug
out off the wall socket, or if the hard disk drive power cable is
disconnected.
Click to expand...
Partly curious. Thank you.
Click to expand...

There was a time where certain drives suffered bad sectors when
this happens. The problem should be solved now.

Writing a sector takes something like 10-20 us. The drive buffer
capacitor should have enough power to keep the electronics working
that long. The disk will detect the power-fail a bit before
it has problems with the voltage levels.

If you short out the power leads, it may be a different story.

Arno
 
Arno Wagner said:
Writing a sector takes something like 10-20 us. The drive buffer
capacitor should have enough power to keep the electronics working
that long. The disk will detect the power-fail a bit before
it has problems with the voltage levels.
Click to expand...
Delusional nonsense. Ronnie also claimed that. Manuals say otherwise.

There is a chipset doc online that says low voltage simply disables the write
head.
 
Alexander said:
Modern journalling file system are sufficiently robust against power loss,
but any unwritten DATA may be lost, causing corruption in the user's files
structure.
Click to expand...

I think that's expressed poorly, because I can interpret it to be either
true or a mis-statement. Vague terms include "unwritten" and "user's
file structure."

A Google of "two phase commitment" might be relevant.
 
Eric Gisin said:
Delusional nonsense. Ronnie also claimed that. Manuals say
otherwise.

There is a chipset doc online that says low voltage simply disables
the write head.
Click to expand...

Instead of a troll, why don't you post a link to that chipset dock.
 
John Doe said:
Instead of a troll, why don't you post a link to that chipset dock.
Click to expand...

The title is Texas Instruments Servo/MSC Product Line User's Guide (PDF).
This is over 5 years old, so things may have changed.

You are better of reading hard drive manuals. IBM's describe the "at most one
bad sector" behavior.

Arnie's "drive buffer capacitor" is a fabrication. You cannot store enough
energy on those dinky caps.
 
After 10 us, 100 uF, 1A, the voltage drops by 100 mV. 100 uF is not a
terribly big capacitor.
 
Previously Alexander Grigoriev said:
After 10 us, 100 uF, 1A, the voltage drops by 100 mV. 100 uF is not a
terribly big capacitor.
Click to expand...

Also you just need to power the write amplifier and circuit
by it, so 1A is probably on the high side.

Personally I find it funny that people who don't know about buffer
capacitors presume to talk about how electronics work. It is one of
the most fundamental things you need to have to get digital
electronics to work right. (In analog electronics they more serve
as filters than as power storage, depending on the circuit
functionality.) I guess these people also never heard of
wire impedances...

Arno
 
Then you and Arnie can show us the picture of a HD controller with that
capacitor, right?

I have never seen an electolytic cap on a HD. They cost money, so you would
never see it on IDE.
 
Well, well, well, someone calling himself "John Doe", calling people troll,
is trying to redo a subject that last time this was discussed resulted
in a thread with a massive 180 posts.
 
Arno Wagner said:
Also you just need to power the write amplifier and circuit
by it, so 1A is probably on the high side.

Personally I find it funny that people who don't know about buffer
capacitors presume to talk about how electronics work. It is one of
the most fundamental things you need to have to get digital
electronics to work right. (In analog electronics they more serve
as filters than as power storage, depending on the circuit
functionality.) I guess these people also never heard of
wire impedances...
Click to expand...
Nobody uses the term "buffer capacitor".

I have a drive with two filter caps marked 6u8. 6.8uF is not going do anthing.

Besides, you also need a blocking diode. Never seen one of those either.
 
Arno Wagner said:
Also you just need to power the write amplifier and circuit
by it, so 1A is probably on the high side.
Click to expand...

Yeah, no need to keep the heads tracking, obviously.
Who cares where that write goes, right Arnie?
Personally I find it funny that people who don't know about buffer
capacitors presume to talk about how electronics work.
Click to expand...

Yes Arnie, that is so funny, especially coming from you.
It is one of the most fundamental things you need to have to get digital
electronics to work right.
Click to expand...
(In analog electronics they more serve as filters than as power storage,
depending on the circuit functionality.)
Click to expand...

Gosh, makes one wonder where Power Amps get their power from and
how they can work with AC signals using asymetric power sourcing.
I guess these people also never heard of wire impedances...
Click to expand...

And then Arnie went from a rush into a delirium ....
 
Off-topic troll.

Folkert Rienstra said:
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Subject: Re: Sudden power loss causes damage?
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Well, well, well, someone calling himself "John Doe", calling people troll,
is trying to redo a subject that last time this was discussed resulted
in a thread with a massive 180 posts.
Click to expand...
 
John Doe said:
Off-topic troll.
Click to expand...

Says he who posts message headers containing email addresses left
right and center all over the internet for the spammers to see..
 
This is correct. There are comparators on the +5 and +12V supply lines.
As soon as one detects an out of limits supply, the write gate is
turned off, for fear that the head may go offtrack and eat into a
neighboring track since the actuator voice coil needs quite a bit of
current (several amps peak - no way you can buffer that with a
capacitor a disk drive manufacturer can afford.) Hence the currently
written sector is incomplete and will result in a read error. It isn't
bad per se, you can overwrite it and it will be fine.
The emergency retract (to the landing zone or load ramp) is powered by
the rotating disk stack, through windage or the motor's back EMF,
sometimes assisted by a spring or a magnet.

Ralf-Peter
 
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